1. Field of the Invention
This invention relates to a disc selecting and controlling method. More particularly, it relates to a disc selecting and controlling method in which one or more disc devices, such as a disc recording/reproducing device or a disc recording medium, is selected from a host computer by way of a disc controller.
2. Prior Art
In general, for selecting and controlling a plurality of disc devices from a host computer by way of a disc controller, a system having the structure as shown for example in FIG. 1 is employed.
Referring to FIG. 1, a host computer 11 is connected by way of interfacing buses, such as GPIB or SCSI, to one or more disc controllers 12, to which one or more disc driving devices or disc drives 13 are connected in a so-called daisy chain connecting configuration by way of drive interfacing buses. In this case, it may be confirmed from the host computer 11 that disc drives 13 exist physically by the interposition of disc controllers 12. It is however presupposed that a disc 14 is allocated to each disc drive 13 without regard to whether the disc is detachable or fixed.
As the disc drive 13, a floppy disc device or a hard disc device has been employed. Recently, a disc reproducing apparatus of the so-called CD-ROM standard employing a small-sized optical digital audio disc as the ordinary digital data recording medium, or a disc reproducing device of the disc as the magneto-optical recording medium, also have come to be employed.
With a consumer player for a small-sized optical digital audio disc, since an inexpensive automatic disc changer in which preset discs may be exchanged automatically for reproduction, as shown for example in the U.S. Pat. No. 4,614,474, is available, the automatic disc changer unit may be applied to the CD-ROM standard disc drive at reduced costs.
When an automatic disc changer, in which plural preset discs are changed automatically for recording and/or reproduction, is used in conjunction with the above described disc selecting and controlling system, unity in the control from the controller 12 would be lost if the automatic changer is connected by way of the disc controller 12 according to the daisy chain connecting configuration. For this reason, as shown in FIG. 1, the automatic changer 20 is connected to an interfacing bus from the host computer 11. In this automatic disc changer 20, there are provided one or more disc drives 21, a number of discs 22 larger than the number of disc drives 21 and a disc exchange control device 23. This is substantially tantamount to connecting the same number of disc drives as the number of the discs 22 by exchanging and attaching the discs 22 to the disc drives 21 by the disc exchange control device 23. Thus, in the automatic disc changer, the discs may also be used as the disc devices in the broad sense of the term.
However, with such conventional system, since the automatic disc changer 20 is directly coupled to the host computer 11, it becomes necessary to provide a disc controller 24 in the automatic changer 20, which is dedicated to the changer, while the control to bring about the same operation as that of the other disc controller 12 from the host computer 11 becomes complicated.
Hence, the automatic disc changer 20 becomes costly to the extent that the disc controller 24 dedicated to the changer and the complicated control software are necessitated. Even if application could be made to the professional system, application to a consumer or personal system can be realized only with difficulty due to the costs, despite the fact that inexpensive automatic disc changers are available for use in conjunction with consumer optical digital audio discs.